1. Field of the Invention
The invention relates to a novel liquid initiator for the accelerated implementation of the polymerisation of lactam, the production thereof, the use thereof and also the utility objects produced therefrom.
2. Discussion of Related Art
Liquid catalysts for the polymerisation of lactam have been known for a fairly long time. They comprise additives to sodium caprolactamate which have the effect that it is liquid at room temperature. These catalysts do not adequately accelerate the polymerisation and must be applied at a relatively high concentration. Examples are DE 2 230 732 C3 and EP 0 438 762 B1. In DE 19 602 683 and DE 19 602 684, liquid catalysts are described for the first time which additionally exert an accelerating effect on the polymerisation. They comprise in particular N-substituted cyclic ureas or N-substituted acid amides, acylation medium for lactam and commercially available sodium caprolactamate, dissolved in lactam-6. It is disadvantageous that they must be applied in a relatively high concentration which can influence the polymer properties, for example the modulus being reduced, an exudation of the solvation components can occur and also the adhesion to optionally used fillers can be impaired.
In DE 197 15 679 A1, a synthesis of liquid catalyst is demonstrated which eliminates many of these disadvantages. Thus lactam-free sodium caprolactamate is produced directly in the solvation medium and converted preferably with carbodiimide. In order to implement the lactam polymerisation, a weight proportion of approximately 1% of such catalysts is quite sufficient.
A liquid multi-component system for implementation of the anionic lactam polymerisation is known furthermore from DE 196 03 305 C2, in the case of which a solvation medium, a catalyst and an activator are used together as a multicomponent system. In the case of this multicomponent system, the individual components are hence used in a solvation form as liquid catalyst. The limited shelf life inter aha is hereby of disadvantage.
In the methods disclosed to date for polymerisation of lactam by means of liquid catalyst with accelerated effect, the used starter material are mainly sodium caprolactamate, acylating compounds and also solvation media. For many applications however, liquid systems are desired which comprise only one component and which contain no sodium caprolactamate and hence can be applied in an even smaller concentration. It is furthermore the objective to make available sodium caprolactamate-free liquid systems which are able to control the start-up phase of polymerisation in a targeted manner.
Furthermore, liquid systems with a long shelf life are of great interest which contain components which positively influence the processing behaviour and also the end product properties, such as for example facilitate the release of the finished parts or else improve oxidation-, heat- and weathering stability.